Pathology Associates Of Lexington, P.A.

Hemoglobin, Urine

Urine dipstick tests (as part of the routine urinalysis) will give a positive reaction at far lower levels than the naked eye can see just by looking at urine color. Myoglobin may cross-react and cause a positive test. The test can be positive whether the hemoglobin is still in red blood cells spilling into urine (from ANY source between the kidney and the specimen collection cup... false positives are often caused by vaginal blood) or free hemoglobin in the urine.

Decreased levels:

"Negative" test = urine is normal with respect only to the issue of hemoglobin.

Increased levels:

"false positive" due to vaginal blood contamination (therefore, the need for "clean catch" urine samples).
presence of indwelling (Foley) catheters causing bladder or urethral bleeding, overt or occult, can be positive.
presence of injuries/toxins or diseases which cause intravascular hemolysis or destruction of red blood cells.
presence of muscle injuries/toxins, medication effects, or diseases which flood the blood with myoglobin.
presence of kidney glomerular "leaks" of red blood cells... on a spectrum from benign hematuria to glomerlonephritis (this tends to leak distorted red blood cells..."microcytes"...which we look for in cytology specimens submitted for hematuria workup).
presence of blood-leaking cancer or disease anywhere within the anatomy of the urinary tract beyond the glomeruli (this tends to leak normal...not "microcyte"...red blood cells).
may be a cross-reacting positive, triggered by myoglobinuria...false positive.

Test Synonyms Other names for this exact or approximate agent are:

hemoglobinuria

(posted 2002; adjusted 23 August 2006)